They look kind of like a blade of grass, but tubular like the green part of a scallion, or green onion. have you ever had garlic you bought in the store sprout in your kitchen? If so, an onion seedling looks alot like that little green sprout. If you are still unsure, you can pinch off the very tip of the seedling and taste it. If it's onion, it will taste like onion. Hope this helps.